In a typical in-ground hydraulic lift system, commonly known as a LPHV lift system, forty to sixty gallons of hydraulic fluid, at a pressure of 100 to 125 p.s.i. are required to raise a car, and 120 to 150 gallons of hydraulic fluid at a pressure of 100 to 350 p.s.i., are required to raise a truck or bus. In recent years, it has been recognized that the use of such large quantities of hydraulic fluid can often give rise to environmental concerns.
Such environmental concerns are due to the commonplace occurrence of hydraulic fluid leaks from most LPHV lift systems. More particularly, hydraulic fluid, while for the most part comprising an oil-based hydrocarbon carbohydrate, can include certain caustic and heavy metal additives including iron, lead, copper, tin, aluminum, nickel, phosphorous, molybdenum and cadmium. These additives, if permitted to penetrate the water table, can contaminate the water supply at concentrations, which, while only a few parts per billion, can accumulate to approach levels that are teratogenic, carcinogenic, or otherwise toxic to humans and/or wildlife. There is, therefore, a burgeoning awareness by environmental officials and others that the in-ground hydraulic lift, which has been a standard in service stations throughout the world since the 1920's, presents an actual and/or potential health hazard of still unmeasured magnitude. This problem is exacerbated in areas where the water table is very high, such as in coastal areas of Florida, Georgia and Louisiana where the water table can be as high as three feet below ground level. Thus, the typical in-ground hydraulic lift, which is installed to a depth of about nine feet in the ground, presents a particularly serious hazard in such areas.
In an effort to minimize the volume of fluid used in the LPHV lift systems, a lift having a slightly higher hydraulic pressure has been developed. Typically, this lift system operates with a pressure of approximately 600 psi, and requires approximately 10 gallons to lift a vehicle. Such an intermediate lift system, however, still requires a significant quantity of fluid, and can still present a threat to the environment. Moreover, because of the quantity of hydraulic fluid needed to lift a vehicle, in combination with the higher pressures being used, it may be difficult to provide the necessary containment precautions to prevent the leakage of hydraulic fluid in the event the lift is damaged.
Another solution, which has been proposed to overcome the problem of the leakage of hydraulic fluid into the ground and water table, has been to further minimizing the volume of hydraulic fluid used in lift systems such that the containment problem becomes easier to address. Associated with such a reduction in volume of hydraulic fluid is an increase in the fluid pressure which must be applied to the hydraulic fluid. In a typical HPLV lift system, a volume of 2.5 gallons of hydraulic fluid, at a pressure of approximately 2,500 psi, can raise a car. Six gallons of hydraulic fluid at the same pressure can raise a truck or bus. Accordingly, it may be seen that in applications such as the lifting of a bus, truck or other heavy duty vehicles, the quantity of fluid required can be reduced to about three percent of that required in a traditional LPHV system.
HPLV systems are known in the art and are commercially offered, for example, by Nusbaum of Germany, Stenhoj of Sweden, and Rotary in the United States. These systems, for the most part, require a service station to excavate the massive concrete and steel structure associated with traditional LPHV systems and replace the low pressure system with a high pressure system. Such excavation is generally quite costly, and may involve the removal of a considerable amount of contaminated soil caused by the previous leaky LPHV system. Therefore, as a practical matter, the use of high pressure lift systems is cost-effective only for new service stations or new auto repair facilities.
In addition to the significant excavation and removal of contamination, the installation of a new HPLV lift system requires that the superstructure, the portion of the lift that is mounted on the upper surface of the plunger and physically engages the vehicle being lifted, must be replaced. This is so because high pressure lifts include a hydraulic ram, or cylinder, which has a smaller diameter than the old low volume plunger, which prevents reuse of the superstructure. As a result, the replacement of low pressure lifts with the more efficient high pressure lifts is often prohibitively expensive.
In addition to the attempt to use HPLV lift systems, a containment device, such as an oversized plastic encapsulation, has been developed for the enclosure and protection of the hydraulics of a lift system. Such a system is offered for sale by Benwil Automotive, and requires the excavation of the old LPHV system in order to install the fluid containment device. Thus, if the existing lift system has caused any amount of environmental contamination, installation of a Benwil Automotive lift would still require the clean-up of the contamination, often at a considerable expense.
Thus, the problem has not been adequately solved and a viable and affordable method for converting LPHV lift systems to HPLV lift systems is needed. Therefore, it is an object herein to provide a method by which LPHV hydraulic lift systems may be cost-effectively replaced by HPLV lift systems. It is also an object herein to provide a method for retrofitting that makes effective use of components of the pre-existing LPHV lift systems by providing a method for retrofitting LPHV hydraulic lift systems which eliminates the need to completely excavate the low pressure systems being replaced.